WO2016079927A1

WO2016079927A1 - Head-up display and vehicle

Info

Publication number: WO2016079927A1
Application number: PCT/JP2015/005330
Authority: WO
Inventors: 聡葛原; 裕昭岡山
Original assignee: パナソニックＩｐマネジメント株式会社
Priority date: 2014-11-19
Filing date: 2015-10-23
Publication date: 2016-05-26
Also published as: WO2016079928A1; US10222614B2; US20170242248A1; EP3223057A4; EP3223057A1; US20170248786A1; JPWO2016079927A1; EP3223057B1; JPWO2016079928A1; JP6582245B2; WO2016079926A1

Abstract

A light beam emitted from the center of a display surface and extending to the center of a perspective region is set as a reference light beam (Lc). The intersecting point between the reference light beam (Lc) and the reflecting surface (121a) of a first reflecting element (121) is set as a reference intersecting point (121c). A plane containing the reference light beam (Lc) incident on the first reflecting element (121) and the reference light beam (Lc) reflected by the first reflecting element (121) is set as a reference plane. An intersecting line between the reference plane and the reflecting surface (121a) of the first reflecting element (121) is set as a reference intersecting line (Bc). A tangential plane to the reflecting surface (121a) of the first reflecting element (121) at the reference intersecting point (121c) is set as a reference tangential plane (170). The respective heights to the reflecting surface (121a) of the first reflecting element (121) from two points consisting of a perpendicular-direction upper point (170u) and a perpendicular-direction lower point (170l) located equal distances from the reference intersecting point (121c) in the reference tangential plane (170) are set as sag amounts. When the perpendicular lines (121u, 121l) intersect the reference intersecting line (Bc), the sag amount at point (170l) is greater than the sag amount at point (170u).

Description

Head-up display and vehicle

The present disclosure relates to a head-up display that allows an observer to visually recognize an image displayed on a display surface of a display device as a virtual image via a projection optical system.

Patent Document 1 discloses a head-up display that includes a Fresnel lens and a concave mirror, expands an image displayed on a display surface with the Fresnel lens, and allows an observer to visually recognize the image as a virtual image. Patent Document 2 discloses a head-up display that includes a lens having a long focal length, enlarges an image displayed on the display surface with the lens having a long focal length, and allows an observer to visually recognize the image as a virtual image.

JP 2007-272061 A Japanese Patent Laid-Open No. 4-247489

This disclosure is intended to provide a head-up display with a small screen distortion in the entire viewpoint area of the observer.

The head-up display according to the present disclosure includes a display device having a display surface that displays an image, and a projection optical system that projects the image displayed on the display surface onto the viewpoint region of the observer. The projection optical system includes a first reflective element and a second reflective element in the order of the optical path from the display surface to the viewpoint area. At least one reflecting surface of the first reflecting element and the second reflecting element has a concave shape. A light beam that is emitted from the center of the display surface and reaches the center of the viewpoint area is set as a reference light beam. The intersection of the reference light beam and the reflection surface of the first reflecting element is taken as the reference intersection. A plane including the reference beam incident on the first reflecting element and the reference beam reflected by the first reflecting element is defined as a reference plane. An intersection line between the reflection surface of the first reflection element and the reference plane is defined as a reference intersection line. A tangent plane with respect to the reflecting surface of the first reflecting element at the reference intersection is defined as a reference tangent plane. On the reference tangent plane, the respective heights from the two points, the upper point in the vertical direction and the lower point in the vertical direction, which are equidistant from the reference intersection point, to the reflecting surface of the first reflecting element are defined as the sag amount. When each perpendicular line that is perpendicular to the reference tangent plane from two points, the upper vertical point and the lower vertical point, intersects the reference intersection line, the sag amount at the lower vertical point Also, the amount of sag at the upper point in the vertical direction is larger.

According to the present disclosure, it is possible to provide a head-up display with small screen distortion over the entire viewpoint area of the observer.

FIG. 1 is a schematic diagram illustrating a vehicle equipped with a head-up display according to the present disclosure. FIG. 2 is a schematic diagram for explaining the head-up display according to the first embodiment. FIG. 3 is a diagram for explaining the relationship between the first reflecting element and the reference light beam according to the first embodiment. FIG. 4 is a diagram for explaining the shape of the projection optical system according to the first embodiment. FIG. 5 is a schematic diagram for explaining a virtual image viewed from the viewpoint region of the observer. FIG. 6 is a diagram illustrating image distortion in the viewpoint region of the observer according to Numerical Example 1. FIG. 7 is a diagram illustrating image distortion in the viewpoint region of the observer according to Numerical Example 2. FIG. 8 is a diagram illustrating image distortion in the viewpoint region of the observer according to Numerical Example 3. FIG. 9 is a diagram illustrating image distortion in the viewpoint region of the observer according to Numerical Example 4. FIG. 10 is a schematic diagram for explaining the head-up display according to the second embodiment. FIG. 11 is a schematic diagram for explaining the head-up display according to the third embodiment. FIG. 12 is a schematic diagram for explaining the head-up display according to the fourth embodiment. FIG. 13 is a diagram showing a coordinate system of Numerical Examples 1 to 4 according to the first embodiment.

Hereinafter, embodiments will be described in detail with reference to the drawings as appropriate. However, more detailed description than necessary may be omitted. For example, detailed descriptions of already well-known matters and repeated descriptions for substantially the same configuration may be omitted. This is to avoid the following description from becoming unnecessarily redundant and to facilitate understanding by those skilled in the art.

It should be noted that the inventor provides drawings and the following description for those skilled in the art to fully understand the present disclosure, and is not intended to limit the claimed subject matter.

(Embodiment 1)
[1-1. Constitution]
[1-1-1. Overall configuration of the head-up display]
Specific embodiments and examples of the head-up display 100 according to the present disclosure will be described below with reference to the drawings.

FIG. 1 is a schematic diagram showing a vehicle 200 equipped with a head-up display 100 according to the present disclosure.

As shown in FIG. 1, the head-up display 100 is disposed inside a dashboard 210 located below the windshield 220 of the vehicle 200.

FIG. 2 is a schematic diagram for explaining the head-up display 100 according to the first embodiment. As shown in FIG. 2, the head-up display 100 includes a housing 140, a projection optical system 120, and a display device 110. The head-up display 100 causes the observer D inside the vehicle 200 to visually recognize the image displayed on the display surface 111 of the display device 110 as a virtual image I. The image displayed on the display surface 111 is reflected through the windshield 220 and guided to the viewpoint region 300 (sometimes referred to as an eyebox) of the observer D, and is visually recognized by the observer D as a virtual image I. .

Here, a light beam forming the upper end of the virtual image I is a light beam Lu. A light beam that forms the lower end of the virtual image I is a light beam Ll. Further, a light beam that forms the center of the virtual image I (a light beam that is emitted from the center of the display surface 111 and reaches the center of the viewpoint region 300) is set as a reference light beam Lc. However, it is assumed that the viewpoint of the observer D is at the center of the viewpoint area 300.

The housing 140 has an opening 130. The opening 130 is provided with a transparent opening cover 131. The opening cover 131 is partially curved. Therefore, external light such as sunlight reflected by the opening cover 131 is difficult to reach the observer D. By making the opening cover 131 into a lens shape, the magnification of the virtual image I can be adjusted. The opening cover 131 is not an essential component in the head-up display 100 according to the first embodiment. Also, the housing 140 is not an essential component in the head-up display 100 according to the first embodiment, and the dashboard 210 of the vehicle 200 may take the place of the housing 140.

The projection optical system 120 includes a first mirror 121 as a first reflecting element and a second mirror 122 as a second reflecting element. The reference light beam Lc reflected by the first mirror 121 and incident on the second mirror 122 has a vector component that is horizontal and directed in the direction toward the display surface 111. Further, the reference light beam Lc emitted from the display surface 111 and incident on the first mirror 121 has a vector component in the forward direction in the vehicle 200. The image displayed on the display surface 111 is reflected through the first mirror 121, then reflected through the second mirror 122, and further reflected through the windshield 220 to reach the viewpoint region 300. The observer D visually recognizes the virtual image I. Here, the viewpoint area 300 refers to a movable area of the eye where the observer D can observe the entire virtual image I without losing the whole.

The display device 110 includes a liquid crystal display device, a backlight unit including a light source, a diffusion plate, a deflection lens, and the like, all not shown. In the display device 110, display image information is controlled by a control unit such as a microcomputer (not shown). On the display surface 111, various information such as road progress guidance, the distance to the vehicle ahead, the remaining battery level of the car, and the current vehicle speed can be displayed as display image information. For the display device 110, a display device such as a liquid crystal display device (Liquid Crystal Display), an organic light emitting diode (electroluminescence), or a plasma display is used. Further, a projector or a scanning laser can be used instead of the display device.

A light shielding wall 150 is disposed inside the housing 140. The light shielding wall 150 prevents stray light that is generated when a light beam emitted from the display surface 111 of the display device 110 directly enters the second mirror 122 without passing through the first mirror 121. The light shielding wall 150 is fixed to the housing 140 by itself. The fixing of the light shielding wall 150 to the housing 140 is not limited to the above embodiment, and the light shielding wall 150 may be fixed integrally with the display device 110 or the second mirror 122.

[1-1-2. Arrangement configuration of projection optical system and display device]
In the head-up display 100 according to the first embodiment, the display device 110 is disposed on the upper side in the vertical direction from the second mirror 122 inside the housing 140. In the display device 110, it is desirable that at least a part of the display surface 111 is disposed above the second mirror 122 in the vertical direction. As a result, the housing 140 can be made compact without the light beam Ll interfering with the second mirror 122.

Further, the display surface 111 of the display device 110 is directed toward the first mirror 121. At this time, it is desirable that the display device 110 is arranged so that the reference light beam Lc emitted from the display surface 111 is inclined with respect to the display surface 111. Thereby, stray light generated when external light enters the inside of the housing 140 and is reflected by the display surface 111 of the display device 110 can be prevented.

Further, the reflection surface 121 a of the first mirror 121 is directed in a direction in which an image displayed on the display surface 111 is reflected on the second mirror 122. Further, the reflection surface 121 a of the first mirror 121 is eccentric so that an image displayed on the display surface 111 is reflected on the second mirror 122.

Here, the reflection area of the second mirror 122 is larger than the reflection area of the first mirror 121 in order to enlarge and display the image displayed on the display surface 111 as a virtual image I. The reflection area is an area of the mirror that reflects incident light. The larger the reflection area, the larger the mirror.

The second mirror 122 is disposed inside the housing 140 closer to the horizontal display device than the first mirror 121. When mounted on the vehicle 200, the second mirror 122 is disposed on the vehicle rear side with respect to the first mirror 121. Further, the reflection surface 122 a of the second mirror 122 is directed in the direction in which the reflected light from the first mirror 121 enters the windshield 220. Further, the reflection surface 122 a of the second mirror 122 is eccentric so that the reflected light from the first mirror 121 enters the windshield 220.

In the first embodiment, the first mirror 121 is a mirror having a reflecting surface 121a having a concave shape and a free-form surface. The second mirror 122 is also a mirror whose reflecting surface 122a has a concave shape and a free-form surface shape. By making the reflecting surface 122a of the second mirror 122 into a concave shape, image distortion generated in the first mirror 121 (image distortion in which the image displayed on the display surface 111 is asymmetrically eccentrically distorted) can be corrected satisfactorily. Can do. In addition, by making the reflecting

surfaces

121a and 122a of the first mirror 121 and the second mirror 122 into a concave shape, the observer D can visually recognize the virtual image I that is enlarged from the image displayed on the display surface 111. . However, only one of the first mirror 121 and the second mirror 122 may have a free-form surface, and the other reflection surface may have a planar shape.

Furthermore, by making the reflecting

surfaces

121a and 122a of the first mirror 121 and the second mirror 122 concave, the power of one mirror can be dispersed, and the distortion aberration sensitivity during assembly can be reduced. it can.

In addition, the first mirror 121 employs a free curved surface shape as the reflecting surface 121a. This is to correct the distortion of the virtual image I caused by the reflection so that a good virtual image I can be seen in the entire viewpoint area 300.

In addition, the second mirror 122 employs a free-form surface as the reflecting surface 122a. This is to correct the distortion of the virtual image I caused by the reflection so that a good virtual image I can be seen in the entire viewpoint area 300.

FIG. 3 is a diagram for explaining the relationship between the first mirror 121 and the reference light beam Lc according to the first embodiment.

The reference light beam Lc is emitted from the center of the display surface 111 of the display device 110, is incident on the reflection surface 121a of the first mirror 121, and is reflected at a reference intersection 121c that is an intersection of the reference light beam Lc and the reflection surface 121a. . At this time, a plane including the reference ray Lc incident on the first mirror 121 and the reference ray Lc reflected by the first mirror 121 is defined as a reference plane. Further, an intersection line between the reflecting surface 121a of the first mirror 121 and the reference plane is defined as a reference intersection line Bc.

FIG. 4 is a diagram for explaining the shape of the projection optical system 120 according to the first embodiment.

The tangent plane with respect to the reflecting surface 121a of the first mirror 121 at the reference intersection 121c is defined as a reference tangent plane 170. On the reference tangent plane 170, a point on the vertical direction that is equidistant from the reference intersection 121c is a point 170u, and a point on the lower side in the vertical direction is a point 170l. Each height from these two points to the reflecting surface 121a of the first mirror 121 is defined as a sag amount. Here, when the perpendicular lines 121u and 121l formed so as to be perpendicular to the reference tangent plane 170 from the two points 170u and 170l intersect the reference intersection line Bc, the point 170u is more than the sag amount at the point 170l. The sag amount at is larger. Thereby, the head-up display 100 with a small screen distortion can be provided in the whole viewpoint area 300 of the observer D.

In the first mirror 121 used in the head-up display 100 according to the first embodiment, the reflection surface 121a has a rotationally asymmetric shape, but the so-called saddle type in which the signs of curvature are different between the X direction and the Y direction. It may have a surface shape.

In the second mirror 122 used in the head-up display 100 according to the first embodiment, the reflection surface 122a has a rotationally asymmetric shape, but the so-called saddle type in which the signs of curvature are different between the X direction and the Y direction. It may have a surface shape.

[1-1-3. Shading wall layout]
The housing 140 includes a light shielding wall 150. As shown in FIG. 4, the light shielding wall 150 is positioned on a virtual line connecting the upper end of the display surface 111 of the display device 110 and the end of the second mirror 122 on the vehicle front side (left side in the drawing).

Thereby, the stray light generated when the light beam emitted from the display surface 111 of the display device 110 directly enters the second mirror 122 without passing through the first mirror 121 can be prevented.

[1.2. Effect]
The effects of the head-up display 100 configured as described above will be described below with reference to FIGS.

FIG. 5 is a schematic diagram for explaining the virtual image I viewed from the viewpoint region 300 of the observer D. In the head-up display 100 according to the first embodiment, the viewpoint area 300 is a rectangle of width 130 mm × length 40 mm.

6 to 9 are diagrams showing image distortion in the viewpoint region 300 of the observer D. FIG. 6 to 9, the solid line indicates the virtual image I projected using the head-up display 100 in each of Numerical Examples 1 to 4. A broken line indicates an ideal shape of the virtual image I when viewed from the viewpoint region 300.

6 to 9, (1) is a diagram illustrating screen distortion when the virtual image I is viewed from the center position of the viewpoint region 300 when viewed from the observer D. (2) is a diagram showing screen distortion when the virtual image I is viewed from the upper left position of the viewpoint area 300. FIG. (3) is a diagram illustrating screen distortion when the virtual image I is viewed from the lower left position of the viewpoint area 300. FIG. (4) is a diagram showing screen distortion when the virtual image I is viewed from the upper right position of the viewpoint area 300. FIG. (5) is a diagram showing screen distortion when the virtual image I is viewed from the lower right position of the viewpoint area 300. FIG.

画面 By using the head-up display 100 according to the present disclosure, the screen distortion is corrected well over the entire viewpoint area 300. That is, in the viewpoint area 300, the observer D can visually recognize a good virtual image I regardless of the position.

Note that in order to visually recognize a better virtual image I, an image to be displayed on the display surface 111 of the display device 110 may be electronically distorted in advance.

[1.3. Desirable conditions]
Hereinafter, conditions that the head-up display 100 according to Embodiment 1 should satisfy are described. In addition, although several preferable conditions are prescribed | regulated with respect to the head up display 100, the structure which satisfy | fills all these several conditions is the most desirable. However, by satisfying individual conditions, it is also possible to obtain a head-up display 100 that exhibits corresponding effects.

The head-up display 100 according to the first embodiment includes a display device 110 that displays an image and a projection optical system 120 that projects an image displayed on the display device 110. The projection optical system 120 includes a first mirror 121 and a second mirror 122 in the order of the optical path from the display device 110.

The head-up display 100 according to the first embodiment projects an image displayed on the display surface 111 of the display device 110 onto the windshield 220 so that the observer D can visually recognize the virtual image I. Thereby, the image displayed on the display surface 111 of the display device 110 can be visually recognized by the viewer D without blocking the front view of the viewer D.

In the head-up display 100 according to the present disclosure, the reflection surface 121a of the first mirror 121 is desirably a free-form surface. Thereby, the screen distortion generated in the windshield 220 can be corrected well, and a good virtual image I with little screen distortion can be visually recognized over the entire viewpoint area 300.

In the head-up display 100 according to the present disclosure, it is desirable that the reflection surface 122a of the second mirror 122 has a free-form surface shape. Thereby, the screen distortion generated in the windshield 220 can be corrected well, and a good virtual image I with little screen distortion can be visually recognized over the entire viewpoint area 300.

In the head-up display 100 according to the present disclosure, the reflection surface 121a of the first mirror 121 has a concave shape or a planar shape. Thereby, compared with the case where the reflective surface 121a of the 1st mirror 121 is convex shape, distortion of the virtual image I which arises by reflection can be suppressed.

In the head-up display 100 according to the present disclosure, the reflection surface 122a of the second mirror 122 has a concave shape or a planar shape. Thereby, compared with the case where the 2nd mirror 122 is convex shape, distortion of virtual image I which arises by reflection can be controlled.

In the head-up display 100 according to the present disclosure, the outer shape of the first mirror 121 is a trapezoid. Thereby, regarding the first mirror 121, an unnecessary area other than the area where the image displayed on the display surface 111 is reflected can be reduced, and the head-up display 100 can be reduced in size. Note that the outer shape of the first mirror 121 is not limited to a trapezoid, and can be changed as appropriate according to the shape of the effective region.

The head-up display 100 according to the present disclosure desirably satisfies the following condition (1).

1.7 <DL1 / DL2 (1)
here,
DL1: Optical path length of the reference light beam Lc between the display device 110 and the first mirror 121 (strictly speaking, the optical path length of the reference light beam Lc between the display surface 111 of the display device 110 and the reflection surface 121a of the first mirror 121) .)
DL2: optical path length of the reference light beam Lc between the first mirror 121 and the second mirror 122 (strictly speaking, the reference light beam Lc between the reflection surface 121a of the first mirror 121 and the reflection surface 122a of the second mirror 122) Optical path length.)
It is.

Condition (1) is a condition that regulates the ratio of the spacing between the display device 110 and the first mirror 121 and the spacing between the first mirror 121 and the second mirror 122. When the condition (1) is satisfied, it is easy to correct the distortion of the virtual image I. Therefore, it is possible to provide the head-up display 100 with a small screen distortion in the entire viewpoint area 300 of the observer D. If the lower limit of the condition (1) is not reached, the surface distance between the display device 110 and the first mirror 121 becomes small. Therefore, the curvature of the concave surface of the first mirror 121 needs to be increased, and the distortion of the virtual image I can be corrected. It becomes difficult. In addition, since the space between the display device 110 and the first mirror 121 is reduced, the effect of the light shielding wall 150 is reduced, and it is difficult to suppress stray light.

Furthermore, by satisfying the following condition (1A), the above effect can be further achieved.

1.7 <DL1 / DL2 <4.0 (1A)
If the upper limit value of the condition (1A) is exceeded, the surface distance between the display device 110 and the first mirror 121 becomes large, and it becomes difficult to provide a small head-up display.

Further, the above-described effects can be further achieved by further satisfying the following condition (1B).

1.7 <DL1 / DL2 <3.0 (1B)
The head-up display 100 according to the first embodiment desirably satisfies the following condition (2).

5 <IL <25 (2)
here,
IL: the exit angle [deg] of the reference beam Lc emitted from the display device 110
It is.

Condition (2) is a condition that defines the emission angle of the reference light beam Lc emitted from the display surface 111 of the display device 110. If the lower limit of condition (2) is not reached, it will be difficult to prevent external light such as sunlight from becoming stray light that reaches the eyes of the observer D. The stray light is generated by reflecting external light such as sunlight in the order of the second mirror 122, the first mirror 121, the display surface 111 of the display device 110, the first mirror 121, the second mirror 122, and the windshield 220. It is stray light. If the upper limit of the condition (2) is exceeded, the contrast of the image displayed on the display surface 111 is lowered, and the visual performance of the virtual image I is lowered.

It is desirable that the head-up display 100 according to Embodiment 1 satisfies the following condition (3).

25 <I2 <45 (3)
here,
I2: incident angle [deg] of the reference light beam Lc incident on the second mirror 122
It is.

Condition (3) is a condition that defines the incident angle of the reference light beam Lc incident on the second mirror 122 from the first mirror 121. When falling below the lower limit of the condition (3), the surface interval between the first mirror 121 and the second mirror 122 becomes large, and the dimension in the depth direction of the housing 140 increases. If the upper limit of the condition (3) is exceeded, it becomes difficult to correct asymmetric distortion generated in the second mirror 122.

In the head-up display 100 according to the first embodiment, it is desirable that the upper end of the light shielding wall 150 is above the straight line connecting the second mirror 122 and the image displayed on the display surface 111. Thereby, the stray light generated when the image displayed on the display surface 111 directly enters the second mirror 122 without passing through the first mirror can be prevented.

(Embodiment 2)
The second embodiment will be described below. Constituent members similar to those in the first embodiment are denoted by the same reference numerals, and detailed description of configurations and functions similar to those in the first embodiment may be omitted.

[2-1. Constitution]
[2-1-1. Overall configuration of the head-up display]
FIG. 10 is a schematic diagram for explaining the head-up display 100 according to the second embodiment. As shown in FIG. 10, the head-up display 100 is disposed inside a dashboard 210 located below the windshield 220. The projection optical system 120 includes a first mirror 121 and a second mirror 122. The image displayed on the display surface 111 of the display device 110 is reflected through the first mirror 121, then reflected through the second mirror 122, refracted through the refractive optical system 160, and further Reflected through the windshield 220. Then, it reaches the viewpoint region 300 of the observer D and is visually recognized by the observer D as a virtual image I.

[2-1-2. Arrangement configuration of projection optical system and display device]
The display device 110 is disposed below the first mirror 121 inside the housing 140. Further, the display surface 111 of the display device 110 is directed toward the first mirror 121. At this time, it is desirable that the display device 110 is arranged so that the reference light beam Lc emitted from the display surface 111 is inclined with respect to the display surface 111. Thereby, stray light generated when external light enters the inside of the housing 140 and is reflected on the display surface 111 of the display device 110 can be prevented.

Further, the reflection surface 121 a of the first mirror 121 is directed in the direction in which the image displayed on the display surface 111 is reflected on the second mirror 122. Further, the reflection surface 121 a of the first mirror 121 is eccentric so that an image displayed on the display surface 111 is reflected on the second mirror 122.

The second mirror 122 is disposed inside the housing 140 on the vehicle front side in the horizontal direction with respect to the first mirror 121. Further, the reflection surface 122 a of the second mirror 122 is directed in the direction in which the reflected light from the first mirror 121 enters the windshield 220. Further, the reflection surface 122 a of the second mirror 122 is eccentric so that the reflected light from the first mirror 121 enters the windshield 220.

The first mirror 121 is a mirror having a reflective surface 121a having a convex shape and a free-form surface. The second mirror 122 is a mirror whose reflecting surface 122a is concave and free-form. By making the reflecting surface 122a of the second mirror 122 into a concave shape, image distortion generated in the first mirror 121 (image distortion in which the image displayed on the display surface 111 is asymmetrically eccentrically distorted) can be corrected satisfactorily. Can do. In addition, by forming the reflecting surface 122a of the second mirror 122 to have a concave shape, the observer D can visually recognize the virtual image I that is enlarged from the image displayed on the display surface 111. However, only one of the first mirror 121 and the second mirror 122 may have a free-form surface, and the other reflection surface may have a planar shape.

Furthermore, by making the reflecting surface 121a of the first mirror 121 into a convex shape, the concave surface power of the second mirror 122 can be increased, and the housing 140 can be downsized.

(Embodiment 3)
Hereinafter, the third embodiment will be described. Constituent members similar to those in the above-described embodiment are denoted by the same reference numerals, and detailed description of configurations and functions similar to those in the above-described embodiment may be omitted.

[3-1. Constitution]
[3-1-1. Overall configuration of the head-up display]
FIG. 11 is a schematic diagram for explaining the head-up display 100 according to the third embodiment.

As shown in FIG. 11, the head-up display 100 is disposed inside a dashboard 210 located below the windshield 220. The projection optical system 120 includes a first mirror 121 and a second mirror 122. The image displayed on the display surface 111 of the display device 110 is reflected through the first mirror 121, then reflected through the second mirror 122, refracted through the refractive optical system 160, and further Reflected through the windshield 220. Then, it reaches the viewpoint region 300 of the observer D and is visually recognized by the observer D as a virtual image I.

[3-1-2. Arrangement configuration of projection optical system and display device]
The display device 110 is disposed above the first mirror 121 inside the housing 140. Further, the display surface 111 of the display device 110 is directed toward the first mirror 121. Thereby, the display surface 111 (liquid crystal surface) of the display device 110 can be prevented from being exposed to sunlight. At this time, it is desirable that the display device 110 is arranged so that the reference light beam Lc emitted from the display surface 111 is inclined with respect to the display surface 111. Thereby, stray light generated when external light enters the inside of the housing 140 and is reflected on the display surface 111 of the display device 110 can be prevented.

Further, the reflection surface 121 a of the first mirror 121 is directed in a direction in which an image displayed on the display surface 111 is reflected on the second mirror 122. Further, the reflection surface 121 a of the first mirror 121 is eccentric so that the image displayed on the display surface 111 is reflected on the second mirror 122.

The first mirror 121 is a mirror whose reflecting surface 121a has a concave shape and a free-form surface shape. The second mirror 122 is a mirror whose reflecting surface 122a is concave and free-form. By making the reflecting surface 121a of the first mirror 121 into a concave shape, image distortion generated by the second mirror 122 (image distortion in which the image displayed on the display surface 111 is asymmetrically eccentrically distorted) can be corrected satisfactorily. Can do. In addition, by forming the reflecting surface 122a of the second mirror 122 to have a concave shape, the observer D can visually recognize the virtual image I that is enlarged from the image displayed on the display surface 111. However, only one of the first mirror 121 and the second mirror 122 may have a free-form surface, and the other reflection surface may have a planar shape. Further, only one of the first mirror 121 and the second mirror 122 may have a concave shape, and the other reflection surface may have a convex shape.

Furthermore, by making the reflecting

surfaces

(Embodiment 4)
Hereinafter, the fourth embodiment will be described. Constituent members similar to those in the above-described embodiment are denoted by the same reference numerals, and detailed description of configurations and functions similar to those in the above-described embodiment may be omitted.

[4-1. Constitution]
[4-1-1. Overall configuration of the head-up display]
FIG. 12 is a schematic diagram for explaining the head-up display 100 according to the fourth embodiment. At this time, for simplicity, a part of FIG. 12 is a projection view.

As shown in FIG. 12, the head-up display 100 is disposed inside a dashboard 210 located below the windshield 220. The projection optical system 120 includes a first mirror 121 and a second mirror 122. The image displayed on the display surface 111 of the display device 110 is reflected through the first mirror 121, then reflected through the second mirror 122, refracted through the refractive optical system 160, and further Reflected through the windshield 220. Then, it reaches the viewpoint region 300 of the observer D and is visually recognized by the observer D as a virtual image I.

[4-1-2. Arrangement configuration of projection optical system and display device]
At least a part of each of the display device 110, the first mirror 121, and the second mirror 122 is arranged in the same horizontal plane.

Further, the display surface 111 of the display device 110 is directed toward the first mirror 121. Thereby, the display surface 111 (liquid crystal surface) can be prevented from exposure to sunlight. At this time, it is desirable that the display surface 111 of the display device 110 is arranged so that the reference light beam Lc emitted from the display surface 111 is inclined with respect to the display surface 111. Thereby, stray light generated when external light enters the inside of the housing 140 and is reflected on the display surface 111 of the display device 110 can be prevented.

(Other embodiments)
As described above, Embodiments 1 to 4 have been described as examples of the technology disclosed in the present application. However, the technology in the present disclosure is not limited to this, and can also be applied to embodiments that have been changed, replaced, added, omitted, and the like. In addition, it is possible to combine the components described in the first to fourth embodiments to form a new embodiment.

(Numerical example)
Hereinafter, Numerical Examples 1 to 4 in which the head-up display according to Embodiments 1 to 4 is specifically implemented will be described. In each numerical example 1 to 4, the unit of length in each table is “mm”, and the unit of angle is “°”. In each numerical example, the free-form surface is defined by the following equation.

Here, z is the sag amount at the position (x, y) from the axis defining the surface, r is the radius of curvature at the origin of the axis defining the surface, c is the curvature at the origin of the axis defining the surface, and k is conic. The constant, Cj, is a coefficient of the monomial x ^m y ⁿ .

FIG. 13 is a diagram showing a coordinate system of numerical examples 1 to 4 according to the first embodiment. In each of Numerical Examples 1 to 4, the reference coordinate origin is the center of the image displayed on the display surface 111, and the X, Y, and Z axes are defined as shown in FIG.

Furthermore, in the eccentric data in each numerical example 1 to 4, ADE means the amount of rotation of the mirror from the Z axis direction to the Y axis direction around the X axis. BDE means the amount of rotation about the Y axis from the X axis direction to the Z axis direction. CDE means the amount of rotation about the Z axis from the X axis direction to the Y axis direction.

(Numerical example 1)
Table 1 shows configuration data of the projection optical system 120 of Numerical Example 1, and Table 2 shows coefficients of the polynomial free-form surface.

(Numerical example 2)
Table 3 shows configuration data of the projection optical system 120 of Numerical Example 2, and Table 4 shows coefficients of the polynomial free-form surface.

(Numerical Example 3)
Table 5 shows configuration data of the projection optical system 120 according to Numerical Example 3, and Table 6 shows coefficients of the polynomial free-form surface.

(Numerical example 4)
Table 7 shows configuration data of the projection optical system 120 of Numerical Example 4, and Table 8 shows coefficients of the polynomial free-form surface.

Table 9 below shows the size of the image displayed on the display surface 111 in each numerical example 1 to 4, the size of the virtual image I, and the distance from the pupil of the observer D to the virtual image I.

Table 10 below shows the numerical values of the conditions (1) to (3) in the numerical examples 1 to 4.

Table 11 below shows the sag amount of the first mirror 121 in the numerical examples 1 to 3. However, the distance from the reference intersection line Bc indicates the vertically upper side when the sign is + and the vertically lower side when the sign is −.

The head-up display according to the present disclosure is suitable for a head-up display that requires high image quality, such as an on-vehicle head-up display.

DESCRIPTION OF SYMBOLS 100 Head-up display 110 Display device 111 Display surface 120 Projection optical system 121 1st mirror (1st reflective element)
121a Reflecting surface of the first reflecting element 121c Reference intersection 121l Perpendicular 121u Perpendicular 122 Second mirror (second reflecting element)
122a Reflecting surface of second reflecting element 130 Opening 131 Opening cover 140 Housing 150 Shading wall 160 Refractive optical system 170 Reference tangent plane 170l Vertical lower point 170u Vertical upper point 200 Vehicle 210 Dashboard 220 Windshield 300 Viewpoint Area D Observer I Virtual Image Bc Reference Intersecting Line Lc Reference Ray Ll Ray that forms the lower end of the virtual image Lu Lu Ray that forms the upper end of the virtual image

Claims

A display device having a display surface for displaying an image;
A projection optical system for projecting the image displayed on the display surface onto the viewpoint area of the observer,
The projection optical system includes a first reflecting element and a second reflecting element in order of an optical path from the display surface to the viewpoint area, and at least one reflecting surface of the first reflecting element and the second reflecting element. Has a concave shape,
A light beam that is emitted from the center of the display surface and reaches the center of the viewpoint region is a reference light beam,
The intersection of the reference ray and the reflection surface of the first reflective element is a reference intersection,
A plane including the reference beam incident on the first reflective element and the reference beam reflected by the first reflective element is a reference plane,
An intersection line between the reflection surface of the first reflection element and the reference plane is a reference intersection line,
A tangential plane with respect to the reflection surface of the first reflective element at the reference intersection is a reference tangential plane,
On each of the reference tangent planes, the height from the two points of the upper point in the vertical direction and the lower point in the vertical direction that are equidistant from the reference intersection point to the reflecting surface of the first reflecting element is defined as the sag amount. ,
When each perpendicular formed so as to be perpendicular to the reference tangent plane from two points of the upper point in the vertical direction and the lower point in the vertical direction intersects the reference intersection line,
The sag amount at the upper point in the vertical direction is larger than the sag amount at the lower point in the vertical direction.
Head-up display.
The reference light beam incident on the second reflective element has a vector component in a horizontal direction toward the display surface,
The head-up display according to claim 1, which satisfies the following condition (1):
1.7 <DL1 / DL2 (1)
here,
DL1: Optical path length of the reference light beam between the display device and the first reflection element DL2: Optical path length of the reference light beam between the first reflection element and the second reflection element.
Mounted on the vehicle,
The reference ray incident on the first reflecting element has a vector component in a forward direction in the vehicle.
The head-up display according to claim 1.
The reflective surface of the second reflective element has a concave shape,
The head-up display according to claim 1.
The reflective area of the second reflective element is larger than the reflective area of the first reflective element;
The head-up display according to claim 1.
The reflective surface of the second reflective element is a rotationally asymmetric free-form surface,
The head-up display according to claim 1.
At least a part of the display surface of the display device is positioned above the second reflecting element in the vertical direction.
The head-up display according to claim 1.
Furthermore, a light shielding wall is provided on a virtual line connecting the upper end of the display surface and the vehicle front side end of the reflective surface of the second reflective element,
The head-up display according to claim 1.
The head-up display according to claim 1, wherein the following condition (2) is satisfied:
5 <IL <25 (2)
here,
IL: Angle of reference beam emitted from the display device [deg]
It is.
The head-up display according to claim 1, which satisfies the following condition (3):
25 <I2 <45 (3)
here,
I2: incident angle [deg] of the reference beam incident on the second reflecting element
It is.
A vehicle comprising the head-up display according to claim 1.